Question 1

Which of the following compounds is a ketone?

Accepted Answer

CH₃COCH₃ (acetone) contains a carbonyl group (C=O) bonded to two alkyl groups, which defines a ketone.

Question 2

What is the functional group present in carboxylic acids?

Accepted Answer

The carboxyl group (-COOH) is the characteristic functional group of carboxylic acids, consisting of a carbonyl group bonded to a hydroxyl group.

Question 3

Which aldehyde is commonly used as a disinfectant and preservative?

Accepted Answer

Formaldehyde (HCHO) is widely used as a disinfectant, antiseptic, and preservative due to its antimicrobial properties.

Question 4

What is the oxidation product of a primary alcohol?

Accepted Answer

Primary alcohols are first oxidized to aldehydes; further oxidation converts them to carboxylic acids.

Question 5

Which carboxylic acid is found naturally in vinegar?

Accepted Answer

Acetic acid (CH₃COOH) is the main component of vinegar, typically present in a concentration of 4-8% by volume.

Question 6

Which of the following compounds will give a positive Tollens test?

Accepted Answer

Aldehydes contain a terminal carbonyl group (-CHO) and are oxidized by Tollens reagent to form a silver mirror, while ketones and carboxylic acids do not give this test.

Question 7

What is the IUPAC name of the compound CH₃-CH₂-CHO?

Accepted Answer

The compound has 3 carbons with a terminal aldehyde group, which is named as propanal according to IUPAC nomenclature.

Question 8

Which reagent is used to distinguish between aldehydes and ketones?

Accepted Answer

Fehling's reagent oxidizes aldehydes to give a brick-red precipitate of Cu₂O, while ketones do not react under these mild conditions.

Question 9

Carboxylic acids boil at higher temperatures than aldehydes or ketones of comparable molecular weight because of:

Accepted Answer

Carboxylic acids form strong intermolecular hydrogen bonds between the carboxyl groups, significantly increasing their boiling points.

Question 10

When formaldehyde (HCHO) is oxidized, the main product is:

Accepted Answer

Formaldehyde is oxidized by mild oxidizing agents to formic acid (HCOOH), the simplest carboxylic acid.

Question 11

Which of the following carboxylic acids is a weak acid in aqueous solution?

Accepted Answer

Acetic acid (CH₃COOH) is a weak acid with partial ionization (Ka ≈ 1.8 × 10⁻⁵), while HCl, HNO₃, and H₂SO₄ are strong acids.

Question 12

The reaction of acetaldehyde with ammonia followed by oxidation produces:

Accepted Answer

Acetaldehyde reacts with ammonia to form an imine intermediate, which upon oxidation yields acetic acid via rearrangement.

Question 13

In the esterification reaction, acetic acid reacts with ethanol in the presence of concentrated H₂SO₄. The product is:

Accepted Answer

Carboxylic acids undergo Fischer esterification with alcohols in acidic conditions to form esters; acetic acid + ethanol → ethyl acetate + H₂O.

Question 14

Acetaldehyde undergoes aldol condensation in the presence of dilute NaOH at room temperature. What is the primary product formed?

Accepted Answer

Aldol condensation of acetaldehyde produces crotonaldehyde after dehydration of the intermediate aldol product.

Question 15

When a carboxylic acid with molecular formula C₅H₁₀O₂ is oxidized using KMnO₄ in acidic medium, it produces a ketone as the main product. Which of the following is the carboxylic acid?

Accepted Answer

3-Methylbutanoic acid has a tertiary carbon adjacent to COOH which resists oxidation; oxidation of the alkyl chain produces the corresponding ketone.

Question 16

Benzaldehyde does not undergo aldol condensation under normal conditions. Which of the following best explains this observation?

Accepted Answer

Benzaldehyde has no α-hydrogens adjacent to the carbonyl carbon, preventing enolate formation which is essential for aldol condensation.

Agniveer Army Technical Aldehydes Ketones & Carboxylic Acids

Aldehydes Ketones & Carboxylic Acids — Practice Questions